Barrel mounting on a pivoted receiver



'2 Sheets-Sheet 1 mm mm m m a Q 0 E 2 m man aw Oct. 15, 1957 c. E.SIMPSON BARREL MOUNTING ON'A PIVOTED RECEIVER Filed June 3, 1954 Oct.15, 1957 c. E. SIMPSON BARREL moun'rxnc ON A PIVOTED RECEIVER -2Sheets-Shes; 2

Filed June 3, 1954 INVENTOR. -Ejirnpanrl w Lu mu HTTUENEYS BARRELMOUNTING ON A PIVOTED RECEIVER Clarence E. Simpson, Wilbraham, Mass.,assiguor to the United States of America as represented by the Secretaryof the Army Application June 3, 1954, Serial No. 434,353 Claims. or.42-75 This invention relates to firearms and more particularly to meansfor affecting the rapid replacement of .barrels therein.

It is well-known that the barrels of automatic firearms become sooverheated and damaged during continuous bursts of fire that they haveto be replaced by another one. Where the firearm is mounted so, that thebarrel protrudes through a barrier, as in a tank, means have tov beprovided for the ejection of the hot barrel to the outside of thebarrier and the installation of another barrel from the inside.

It is, therefore, an object of this invention to provide in an automaticfirearm simple and reliable means for rapidly changing a barrel therein.

It is another object of this invention to provide in automatic firearmsmeans for pivotally mounting the receiver thereofso that a barrel may beinstalled into the barrel jacket of the firearm from the rear endthereof.

It is still another object of this invention to provide in an automaticfirearm having a pivotal receiver, foolproof means for securing theoperating parts in the receiver when rotated for the replacement ofbarrels.

It is a further object of this invention to provide in automaticfirearms having a pivotal receiver, quick-change barrel means operatedby the pivotal movement of the receiver. a

It is a still further object of this invention to provide for automaticfirearms, means in unitary relationship with the receiver for freeing abarrel from the barrel jacket and to move and lock another barreltherein at the proper headspace position.

j The specific nature of the invention as well as other objects andadvantages thereof will clearly appear from a description of a preferredembodiment as shown in the accompanying drawings in which:

Fig. l is a fragmentary partially cross-sectioned side view of a firearmin the recoil position; t

Fig. 2 is a view taken along line 22 of Fig.1;

Fig. 3 isa view taken along line 33 of Fig. 1;

Fig. 4 is a fragmentary partially cross-sectioned view of the firearmshowing the barrel moved rearwardly by the receiver and, in phantom, thebarrel ejected forwardly from the barrel jacket;

Fig. 5 is a fragmentary perspective view of the barrel locks in positionto move the barrel to a locked position; and

Fig. 6 is a view similar to Fig. 5 but showing the barrel locks inposition to move the barrel rearwardly.

Shown in the figures is a barrel jacket 12 having an upwardly opensemicylindrical ledge portion 9 extending forwardly from the lowerportion thereof, a receiver 13 pivotally mounted to barrel jacket 12 forupward rotation by a transverse pin 14 and a barrel '15 slidably mountedin the barrel jacket. Assembled within receiver 13 are operating parts(not shown) actuatable by a slide member 16 which is in a disconnectrelationship with an operating rod 17 in barrel jacket 12 so as topermit piv- States Patent.

ice

otal, upward opening of the receiver. Receiver 13 is provided with anannular flange portion 18 which is matingly received by an extensionportion 19 on the rear end of barrel jacket 12. Rotatably mountedthrough flange portion 18 is a transverse latch pin 20 having anexternal knob 21, a flat portion 22 extending between the inner walls ofthe flange portion and a semicylindrical portion 23 formed by flatportion 22. Pin 20 is so arranged that when in a latched position slide16 and operating rod 17 reciprocate over portion 22 and when turned toan unlatched position semicylindrical portion 23 is moved upwardly toblock forward movement of slide 16. Arcuate recesses 24 and 25 in theadjacent sides of slide 16 and operating rod 17, respectively, permitrotation of portion 23 when the firing mechanism of the firearm is inthe recoil position. Extending forwardly from the rear side of extensionportion 19 of barrel tions 28 which are in alignment with thelongitudinal axis of barrel 15. Lock portions 28 are comprised of armportions 29, which extend forwardly to flange portion 18, and lugportions 31) which extend inwardly therefrom. The front and rear sidesof lugs 39, noted at 41 and 42, respectively, are arranged to bevertical with the longitudinal axis of barrel 15 when receiver 13 islatched to barrel jacket 12 and the lower rear corner of each lug 30 iscut to form a diagonal portion 31 to be further described hereinafter.The junction of diagonal portion 31 with rear side 42 forms corner 39and the junction of the diagonal portion with the bottom side of the lugforms corner 40.

-Barrel 15 is provided with a radially disposed pin 32 which is fixedlyassembled, as by press fit, into a hole 33 provided in the outer wall ofthe barrel and is arranged to be slidably received in a longitudinalchannel 34 along the top inner side of barrel jacket 12. Spaced from thebreech end of barrel 15 is a pair of laterally opposed vertical chordalrecesses 35 arranged to snugly receive lugs 30 therein when receiver 13is latched to barrel jacket 12 and thereby securely lock the barrel toreceiver 13 in battery position. Longitudinal chordal cuts 36 arearranged to receive arm portions 29 when lugs 30 are received byrecesses 35 and extending forwardly from recesses 35 are triangularclearances 37 which. form cam surfaces 38 which extend upwardly andforwardly from front side 41 approximately midway of the top side oflugs 30. The junctions of the front sides of recesses 35 and camsurfaces 38 form apex portions 43 and the junctions of the bottom sidesof lugs 31? with front sides 41 thereof form pivotal portions 44.

Operation When a barrel 15 is to be replaced in barrel jacket 12 thefiring mechanism of the firearm is actuated to recoil position and thenknob 21 is rotated to unlatched position wherein portion 23of latch pin20 is rotated upwardly to be received by slot 26. Thus, receiver 13 isfree to be swung upwardly and, as has hereinbefore been explained, whenpin 20 is in unlatched position portion 23 thereon blocks slide 16 fromcoming out of the receiver. During the initial rotation of receiver 13,the corners 39 press rearwardly against rear walls 45 of recesses 35 andduring continued upward swing of the receiver such corners move alongsuch walls to carnrningly move barrel 15 rearwardly until diagonalportions 31 are parallel with walls 45. Thereafter, corners 40 cammingly engage walls 45 to continue camming barrel rearwardly unt l lugs arefre e of the barrel; In the meantime, the top portions of front sides 41are rotated forwardly mto clearances 37. It is clearly apparent thathereby considerable leverage is placed against barrel 15 to break anyadhesion thereof with barreljacket 12 as by carbon deposits producedduring fire.

When receiver 13 is swung away from the breech of barrel 15, the barrelmay be either pulled inwardly from barrel jacket 12 or pushed outwardlytherethrough by another barrel. The forwardly projecting ledge 9 permitsbarrel 15 to tilt freely from barrel jacket 12 and drop therefromwithout jamming.

The unused barrel 15 is installed in barrel jacket 12 so that pin 32therein aligns with channel 34 in the barrel jacket and thereby alignsbarrel locks 28 with recesses 35. When barrel 15' is pushedapproximately into locked position in barrel jacket 12, receiver 13 isswung down whereby pivotal portion 44 engages cam surfaces 38 so thatcontinued downward rotation of receiver 13 moves barrel 15 camminglyforward with diagonal portions 31 providing clearances to permitrotation of lug 30 past the junction of walls 45 of recesses and thebottom sides of longitudinal cut 36. When receiver 13 is fully rotateddownwardly, lugs 30 are snugly received by recesses 35 as hereinbeforeexplained to securely lock barrel 15 to receiver 13 in battery position.

It is clearly apparent from the foregoing that there is here providedasimple, rugged and reliable means for rapidly changing barrels in anautomatic firearm.

Although a particular embodiment of the invention has been described indetail herein, it is evident that many variations may be devised withinthe spirit and scope thereof and the followng claims are intended toinclude such variations.

I claim:

1. A firearm having a barrel jacket provided with a peripheralrearwardly extending portion, said portion being provided with laterallyopposed slots which extend forwardly from the rear end thereof and beingterminated by a larger cylindrical hole, a barrel slidably mounted insaid barrel jacket, a ledge portion extending from the front end of saidbarrel jacket to assist in jam-free removal of said barrel therefrom, areceiver provided with a slide reciprocable into said barrel jacket,said receiver being mounted to said barrel jacket for pivotal movementbetween a closed position and an open position relative to said barreljacket and being provided with a peripheral flange for receiving saidportion when in said closed position, a pair of opposed barrel lockingportions in said receiver provided with angular portions rotatablyreceivable in cooperating recesses in said barrel to securely lock saidbarrel to said receiver in battery position, cam surfaces in saidrecesses engageable by said angular portions for translationof pivotalmovement of said receiver to rearward or forward movement of saidbarrel, and a latch pin mounted in said receiver for releasably latchingsaid receiver to said barrel jacket when in said closed position andforrotation between a latched and an unlatched position, said latch pinbeing provided with a flat portion to allow reciprocation of said slidethereover when said latch pin is in said latched position and asemicylindrical portion formed by said flat portion, saidsemicylindrical portion being positionable to block movement of saidslide from said receiver when said latch pin is rotated to the unlatchedposition and being slidably receivable when in said unlatched positionby said slot and rotatably receivable by said cylindrical hole when saidlatch pin is turned to said latched position whereby said receiver isblocked from opening.

2. A firearm having a barrel jacket, a barrel slidably mounted in. saidbarrel jacket for removal from the front thereof, a ledge portionextending from the front end of aid barrel jacket to assist in jam-freeremoval of said barrel, a receiver pivotally mounted to said barreljacket to provide for rearward removal of said barrel and being providedwith a slide reciprocable into said barrel jacket, a pair of laterallyopposed barrel lock portions provided on the inside of said receiver,each of said barrel locks being provided with an arm portion, and aninwardly projecting lug portion, said lug portion being provided with afront side and a rear side vertical to the longitudinal axis of saidreceiver, a bottom side and a diagonal portion which forms cornerportions at the junction thereof with said rear side and said bottomside of said lug portion, recesses in said barrel for receiving saidbarrel locks, each of said recesses being providedwith a front wall anda rear wall cooperable with said front side and said rear side of thecooperating one of said lugs for locking said barrel to said receiver inbattery position, said rear wall being cammingly engageable by saidcorner portions during pivotal rotation of said receiver from saidbarrel jacket whereby said barrel is moved rearwardly, cam surfacesextending upwardly and forwardly from said front walls and beingengageable by said lug portions during rotation of said receiver to joinsaid barrel jacket whereby said barrel is moved into said batteryposition to be locked by said barrel locks, and a latch pin mounted insaid receiver for releasably latching said receiver to said barreljacket and being rotatable between a latched and an unlatched position,said latch pin being provided with a flat portion which allowsreciprocation of said slide thereover when said latch pin is in thelatched position and a semicylindrical portion formed by said flatportion for blocking movement of said slide from said receiver when saidlatch pin is rotated to the unlatched position. 7

3. A firearm having a cylindrical barrel jacket, a barrel mounted insaid barrel jacket for slidable removal from the front end thereof bythe installation of a replacement barrel, a pair of recesses disposed inopposite sides of said barrel, linear walls formed by said recesses, areceiver mounted to said barrel jacket for pivotally unblocking the rearend thereof to permit the installation of said replacement barreltherein from the rear end, and lug means on said receiver camminglycooperative with said walls for moving said barrel rearwardly in saidbarrel jacket to an unlocked position during pivoting of said receiverto unblock the rear end of said barrel jacket and forwardly to a lockedbattery position during pivoting of said receiver to normal positionwherein the rear end of said barrel jacket is blocked thereby with saidlug means being engageably cooperative with said walls for locking saidbarrel to said receiver in said battery position.

4. A firearm having a cylindrical barrel jacket, a barrel replaceablymounted in said barrel jacket for slidable removal from the frontthereof by the installation of a replacement barrel therein from therear, linear cam means dlsposed on opposite sides of said barrel, aledge portion extending from the front end of said barrel jacket toprovrde am-free removal of said barrel when slidingly ejected from saidbarrel jacket, a receiver mounted to said barrel acket to pivotallyunblock the rear end thereof and permit installation of said replacementbarrel from the rear end of said barrel jacket, and barrel locking meansin said receiver cooperable with said cam means provided in said barrelfor slidably moving said barrel rearwardly in said barrel jacket duringpivoting of said receiver to unblock the rear end of said barrel jacketand forwardly during p voting of said receiver to normal positionwherein the rear end of said barrel jacket is blocked thereby and forlocking said barrel to said receiver in battery position.

5. A firear m having a cylindrical barrel jacket, a barrel mounted insaid barrel jacket for slidable removal from the frontend thereof by theinstallation of a, replacement barrel from the. rear end of the barreljacket, a ledge. portion extending from the front end of said barreljacket to provide jam-free removal of said barrel when slidingly ejectedfrom said barrel jacket, a receiver mounted to said barrel jacket forpivotally unblocking the rear end of said barrel jacket for installationof said replacement barrel into said barrel jacket from the rear endthereof, a pair of opposed barrel locking lugs in said receiverreceivable by opposed recesses in said barrel for securely locking saidbarrel to said receiver in battery position, cam surfaces formed by saidrecesses, and pivotal portions on said locking lugs cooperable with saidcam surfaces for slidably moving said barrel in said barrel jackettoward and away from said battery position responsive to rotation ofsaid receiver. 7

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES fEinzelausbildungam M. G. 42, a manual, especially pages 14and 15.

